Section 11.9 You re Being Tracked

   


11.9 You're Being Tracked

graphics/onedangerlevel.gif

Thirty years ago when the mainframe was king, it was common for manufacturers to include a serial number in computer hardware. This allowed the custom-built software to check that it was being run only on the computer that it was licensed for. With the mass-produced microprocessor and shrink-wrapped software, this practice became too expensive. Certainly, software companies have suffered substantial lost profits from illegally copied software. This trend seems to be reversing. It is not yet clear if this is a trend or a "flash in the pan." This raises some interesting legal questions, too.

11.9.1 The Pentium III Serial Number

graphics/onedangerlevel.gif

The Pentium III processor has a serial number readable by any code that runs on it. Intel states that the intent was to enable e-commerce sites to confirm that the person placing an order is on the same system that opened the account, to reduce fraud. Certainly, it could also be used to cut down on pirated software. There was quite a storm of outrage that this was a violation of people's right to privacy, etc. Intel offered a way to "disable" this feature.

The loyal opposition offered ways to disable this disablement so that code still could read the serial number. The controversy seemed to die down when someone pointed out that each Network Interface Card (Ethernet card), present on most computers today, has a MAC address that is unique. Had Intel explained it as a way to track stolen computers, it might have been accepted.

11.9.2 Microsoft's GUID Allows Spying on You

graphics/onedangerlevel.gif

When users register their Microsoft software, inside the shrink-wrapped package is a unique registration number that they must key into their system when loading the software. This is a serial number and a checksum of it. The checksum makes it harder for someone to make up a fake serial number. This is common practice in the software industry and an inexpensive way to serialize software to reduce the likelihood of theft. Someone else cannot use the software without a valid registration number.

Microsoft went a step further. Every document generated by Word and Excel has hidden in it what Microsoft calls the Globally Unique Identifier or GUID. This GUID consists of the registration number and the unique MAC address of the Network card (Ethernet card).

Technically, the GUID uses what the software driver reports to be the MAC address. It is not too hard to trick the driver into saying the MAC address of one's rival's system when writing an anonymous expose of the boss.


Although the MAC address is broadcast over the LAN as a way of associating a system's IP address with the actual system, the MAC address normally does not get beyond your LAN. The only way for someone beyond the LAN to see your MAC address is for a program running on the computer (or another computer on the LAN) to read it and include it in a message. Samba is the only standard program on Linux that transmits this MAC address beyond the Ethernet segment, as far as I know.

However, Microsoft's Word and Excel programs put the GUID in every document created. This allows every such document to be traced back to the machine and, thus, the person who wrote it. Is this a violation of privacy? Many think so. How harmful is it?

Suppose you write a Word document on your office win95 system exposing the illegal activities of the company you work for. You want to remain anonymous, so you do not include your name. You store the document on a floppy and mail it anonymously to the district attorney (government prosecutor).

A month later you are fired for bogus reasons. (It would make for more drama to talk about bullets flying from big black cars in the middle of the night, but that stuff only occurs in the movies.) What happened? Because a criminal defendant has the right to see all evidence against it, the company got to examine the floppy and read the GUID. They then checked all their computers until they found a match.

Is this a real possibility? Yes. Has it hurt anyone? The GUID in the Word document that was the Melissa virus tied it to David Smith, its author. Although the GUID was not used to catch him, it was corroborating evidence.

Microsoft offers a patch to prevent the GUID from being placed in documents.


   
Top


Real World Linux Security Prentice Hall Ptr Open Source Technology Series
Real World Linux Security Prentice Hall Ptr Open Source Technology Series
ISBN: N/A
EAN: N/A
Year: 2002
Pages: 260

flylib.com © 2008-2017.
If you may any questions please contact us: flylib@qtcs.net